The Greek arén refers to a lamb — a young sheep. It is one of several Greek words for lamb, used in the New Testament alongside amnós (lamb) and arnion (little lamb).
Arén appears once in the New Testament in Luke 10:3, where Jesus sends out the seventy-two 'like lambs among wolves' — a vivid image of vulnerable, unarmed witnesses sent into hostile territory with nothing but the power of the gospel. The lamb/wolf imagery picks up Old Testament themes of the messianic age when 'the wolf will live with the lamb' (Isaiah 11:6; 65:25). The disciples as lambs are commissioned to bring that peaceable kingdom into reality through proclamation. Their vulnerability is not a weakness but a feature — the power of the gospel works through apparent weakness.